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How red and yellow soil are formed why do they look red?

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  • Difficulty Level : Hard
  • Last Updated : 19 Jul, 2022
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Red soil is a particular kind of soil distinguished by its reddish hue. In warm, humid climates like those found in tropical and subtropical countries, red soil can be found. Usually, it is ideal for agriculture and is fertile. Rocks containing iron oxides weather and turn into red soil. Basalt is the most typical form of rock that contributes to the red soil. Basalt is broken down into smaller pieces during the weathering process, and the smaller particles are then further broken down into silt and clay.

The soil’s crimson hue is a result of the iron oxides in the rocks. Red soil has a high content of organic matter and nutrients including nitrogen, phosphorus, and potassium, which contribute to its fertility. These nutrients are crucial for the development of plants. Additionally, red soil has good drainage, which is crucial for farming. Red dirt promotes plant growth. The iron oxide in the rocks is what gives the soil its red colour. Red soil’s high quantities of organic matter and nutrients are what give it its fertility. Red soil has good drainage, which is crucial for farming.

Red Soil

The development of red soil is commonly thought to occur in warm, humid areas. They often grow in mixed forests and are deciduous in development. They have thin organic and mineral layers on top of a leached layer that is yellowish-brown and rests on an illuvial red layer. Typically, iron-rich sedimentary rocks are the source of red soils. These soils have poor growing conditions and are not suited for cultivation due to their low nutrient content.

Types of Red Soil

  1. Red Clay Soil: These are regarded as mineral soils because they don’t include any calcareous material. These soils have a saturation base of less than 35% over the entire soil and have 10 per cent fewer weatherable minerals in the very top layer.
  2. Red Loam Soil: The breakdown of granite, gneiss charnockite, and diorite rocks produces this red loam soil. These soils are discovered to be clumpy, permeable, and lacking in elements necessary for concretion.
  3. Red Laterite Soil: These soils are abundant in iron and aluminium. They typically occur in humid, hot tropical climates. These soils are red because they contain iron oxide, a mineral that gives soil its colour. These soils form when the parent rock beneath them begins a sustained and severe weathering process.
  4. Red Yellow Soil: It develops beneath forests with large leaves. These kinds of forests are typically found in humid subtropical areas. It is thought that these soils undergo an acid reaction. These soils have a much lower humus content than other soils. The soil’s reddish-yellow hue is caused by ferric hydroxide, which can be found there.
  5. Red Sandy Soil: The soil in question is thin, warm, and dry. They are typically deficient in nutrients and tend to be acidic. Because there is a higher proportion of sand and less clay in red sandy soil, it is typically referred to as light soil.

Features of Red soil and yellow soil

  1. Iron oxide is abundant in red soil, which is also permeable.
  2. Red soil is shallow and has a pH value between 6.6 and 8.0.
  3. Red soil is unproductive, yet it accepts fertilisers.
  4. These are poor-growing soils that are also deficient in humus and nutrients, making them challenging to develop.
  5. Large areas of Western Tamil Nadu, Karnataka, Southern Maharashtra, Chhattisgarh, Telangana, Andhra Pradesh, Odisha, and the Chhota Nagpur plateau of Jharkhand include these soils.


  1. Because it is productive and well-drained, red soil is frequently utilised in agriculture. It is especially helpful for crops like sugarcane and bananas that need a lot of nutrients. Other crops, such as vegetables and fruits, can also be grown on red soil.
  2. These crops are grown in red soil because it is rich in nutrients like nitrogen, phosphorus, and potassium that are essential for plant growth. Additionally, the land has good drainage, which is crucial for farming.

Why does Red Soil Look Red?

The hue of red soil can range from red to brown, yellow, grey, and even black in rare circumstances. Since iron oxide is reddish-brown in colour, red soil has a relatively high concentration of iron in it, which accounts for its hue. The usual nutrients like nitrogen, humus, phosphoric acid, lime, magnesium, etc. are insufficient in red soil, but it is relatively rich in potash, and the soil’s pH ranges from neutral to acidic. Old crystalline and metamorphic rocks, primarily acid granites, quartz rocks, gneiss, and feldspathic rocks, weather to produce it.

Red soil is mostly siliceous and aluminous chemically, with some free quartz present as sand, but it is also highly potassium-rich. Sand to clay may be present in red soil, although loamy soil makes up the majority of it. The upper layer of red soil is primarily sand and permeable, while the lower layer is dark in colour and extremely fruitful. Thus, one may produce a great number of different crops, such as cotton, millets, wheat, rice, oilseeds, pulses, tobacco, and fruits, with the right application of fertilisers and irrigation.

Sample Questions

Question 1: How is soil formed?


Weathering of rocks, commonly referred to as parent material, produces soil. Rocks can weather in two different ways: physically and chemically.

Question 2: What is meant by reforestation?


Reforestation is the large-scale planting of new trees or the renewal of existing ones to replace lost or dying forests.

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